Behavior change between Debug and Release modes with XCode7 and Swift2

EnumFailed.swift

enum MyEnum {
  case Foo
  case Bar(param: Int)
  case Baz

  func isFoo() -> Bool {
    if case .Foo = self {
      return true
    }

    return false
  }

  func isBaz() -> Bool {
    if case .Baz = self {
      return true
    }

    return false
  }
}

let a: MyEnum = .Baz

print(a.isFoo()) // "false" in debug mode, "true" in release mode